JP2007113650A - Work vehicle - Google Patents

Abstract

A work vehicle capable of automatically and appropriately switching on and off a diff lock mechanism according to a traveling state.
Rotational power of an engine 6 is transmitted to left and right front wheels 2 and rear wheels 3 via differential devices 50F and 50R equipped with differential lock devices 37A and 37B. If the drive switching device 5g is in the 2WD state, it is switched to the 4WD state, and the differential lock on / off switch 67 is turned off to place the 2WD 4WD change device 5g in the 4WD state.
In this way, it is possible to prevent the differential lock devices 37A and 37B from being forgotten to be cut, and the straight traveling performance and operability of the work vehicle are improved as compared with the prior art.
[Selection] FIG.

Description

  The present invention relates to a traveling vehicle such as an agricultural tractor, and more particularly to a shift control device thereof.

Conventionally, a traveling vehicle such as an agricultural tractor is provided with a differential lock device that locks the differential action on the transmission system of the front wheels or the rear wheels, and the differential lock device is turned on and off by an energization output of a controller. ing. For example, the following patent document shows a control mechanism for smoothly turning by making the front wheel diff-lock when turning in a wet field.
Japanese Patent Laid-Open No. 10-181374

The differential lock mechanism of the above-mentioned Patent Document 1 is a control that improves the turning performance in a field in a wet paddy field such as a scratching work, but in a general dry paddy field work, if the differential lock mechanism is operated during a turn, The swirl remains on the dry field and the field becomes rough. Also, when performing various operations such as raising / lowering operation of the work implement, rolling operation, turning operation, etc. while working with the tractor, the operation of the differential lock mechanism may be forgotten.
An object of the present invention is to provide a work vehicle capable of automatically and appropriately switching on and off a diff lock mechanism according to a traveling state.

The above-described problems of the present invention are achieved by the following solution means.
The present invention transmits the rotational power of the engine (6) to the left and right front wheels (2) and the rear wheels (3) via a differential device (50F, 50R) equipped with a differential lock device (37A, 37B). (2) Two-wheel drive / four-wheel drive switching device (5g) for switching between a two-wheel drive state in which only the drive is driven and a four-wheel drive state in which the front and rear wheels (2, 3) are driven together, and a two-wheel drive for switching the switching device (5g) In a work vehicle having a four-wheel drive switching actuator (32), a diff lock on / off switch (67) for turning on / off the diff lock device (37A, 37B), and a diff lock device (37A) by turning on / off the diff lock on / off switch (67). , 37B) actuators (37a, 37b) for turning on and off,
If the two-wheel drive / four-wheel-drive switching device (5g) is in the two-wheel drive state when the differential lock on / off switch (67) is turned on, it is switched to the four-wheel drive state, and when the differential lock on / off switch (67) is turned off, If the 4WD switching device (5g) is in the 4WD state, the 4WD state is changed to the 4WD state, and the 2WD 4WD switching device (5g) is not switched to the 2WD state until the 2WD state is reached. A work vehicle including the device (C).

  According to the present invention, both the front wheel (2) and the rear wheel (3) are provided with the differential lock device (37A, 37B). Further, it is assumed that the switch is turned on / off by a single switch (67). In this case, if the switch (67) is turned on (turned on when it is easy to slip and wants to go straight), if it is in a two-wheel drive state, a slip may occur on the front wheel (2) side, which may ruin the field. However, in order to eliminate the inconvenience, there is a troublesome operation of the 2WD 4WD changeover switch to 4WD again.

  According to the present invention, forgetting to cut when the diff lock device (37A, 37B) should be cut off is prevented, and the straight traveling performance and operability of the work vehicle are improved as compared with the prior art.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the tractor 1 is a four-wheel drive vehicle equipped with a wheel-type travel device. The tractor 1 has an engine 6 mounted on the center upper portion of the engine mounting frame 4 at the front of the vehicle body. Is transmitted to the front wheels 2 and 2 on the left and right of the front of the aircraft and the rear wheels 3 and 3 on the left and right of the rear of the aircraft via a transmission mechanism in the transmission case 13. Further, when the handle 7 is rotated left and right, the left and right front wheels 2 and 2 are steered via a power steering device.

  Also, lift arms 8 and 8 that are turned up and down by a lifting cylinder 43 are provided at the rear part of the machine body. The front ends of the lift arms 8 and 8 and the intermediate portions of the lower links 9 and 9 for mounting the work machine are connected by lift rods 11 and 11, and are connected to the rear ends of the upper link 10 and the lower links 9 and 9. A ground work machine (rotary work machine 12 in the illustrated example) is connected, and the lift arms 8 and 8 are turned up and down to raise and lower the rotary work machine 12.

  As shown in FIG. 3, the rotational power of the engine 6 is input to the transmission case 13 through the main clutch 5a, and the power through the main clutch 5a is the driving power for driving the front wheels 2, 2 and the rear wheels 3, 3. And branching transmission to two systems of work machine power. The traveling system power is transmitted to the rear wheel differential device 50R through a traveling transmission device 5e including a forward / reverse transmission portion 5b, an eight-stage main transmission portion 5c, and a high, middle and low three-stage sub-transmission portion 5d. The rear wheels 3 and 3 are driven. The power shifted by the travel transmission 5e is taken out to the front side of the transmission case 13 via the 4WD switching device 5g, and transmitted to the front wheel differential device 50F in the front axle case via the front wheel transmission shaft 5h. It is transmitted to the front wheels 2 and 2. Further, between the differential shafts and the output shafts of the front and rear differential devices 50F and 50R, there are provided differential lock devices 37A and 37B for locking the differential action, and the differential lock devices 37A and 37B are turned on and off by driving the differential lock cylinders 37a and 37b. It is the composition to do.

  The work machine system power is taken out from the forward / reverse transmission portion 5b to the PTO shaft 14 projecting rearward from the rear surface portion of the transmission case 13 via the PTO forward / reverse switching device 5j and the PTO transmission device 5k. 12 is transmitted.

  Further, as shown in FIG. 2, the main transmission unit 5 c performs an increase / decrease operation step by step by pressing the transmission up switch 47 and the transmission down switch 48 provided on the grip of the transmission lever 15, and the sub transmission unit 5 d A shift operation of the lever 15 shifts the height.

  Next, the hydraulic configuration of the tractor 1 will be described with reference to FIGS.

    The hydraulic pressure discharged from the hydraulic pump 16 is first branched to the left and right brake cylinders 19 and 19 via the brake valve 18 on the upper side of the circuit via the ladies valve 17. The brake valve 18 is configured integrally with a flow control valve 18a for adjusting the braking force and a switching control valve 18b for selecting the rear wheel 3 to be braked.

  Similarly, in order from the upper side of the hydraulic circuit, the front and rear clutch control valves 21a and 21b are branched to the forward / reverse switching clutch cylinder 22 of the forward / reverse transmission portion 5b to switch the 1-2 speed of the main transmission portion 5c. The first transmission control valve 23 is branched to the first transmission cylinder 24. Further, the second transmission control valve 26 for switching the 3-4 speed of the main transmission unit 5c is branched to the second transmission cylinder 27, and the auxiliary transmission control valve 28 for switching the height of the auxiliary transmission unit 5d is used for the auxiliary transmission. Branching to the cylinder 29, branching to the 2WD 4WD switching cylinder 32 via the 2WD 4WD switching control valve 31 for 2WD 4WD switching of the 4WD switching device 5g.

  Further, the PTO transmission control unit 33 branches to the PTO transmission cylinder 34 via the PTO transmission control valve 33 for switching the height of the PTO transmission device 5k, and through the differential lock control valve 36, the front wheel diff lock cylinder 37a for the front wheel diff device 50F, and the rear wheel The structure is branched to the rear wheel differential lock cylinder 37b for the differential device 50R.

  Also, the hydraulic pressure from the hydraulic pump 16 shown in FIG. 4 is taken out from the hydraulic pressure control device 39 through the external hydraulic pressure take-out device 38, and is supplied to the horizontal cylinder 41 via the horizontal control valve 39 for horizontal control of the work equipment shown in FIG. In addition, the hydraulic pressure that is sent through the horizontal control valve 39 is sent to the left and right lift cylinders 43 via the work implement lift control valves 42 and 42.

  Next, based on FIG. 7 and FIG. 8, the structure of the control part C which consists of each controller 46 and 48 connected by the communication line is demonstrated.

    As shown in FIG. 7, various switches and sensors are connected to the input side of the travel controller 46 as follows. That is, a shift up switch 47 that shifts the main transmission 5c step by step to the high speed side, a shift down switch 48 that shifts the main transmission 5c transmission step by step to the low speed side, and the shift position of the sub shift lever 15 are detected. A shift lever position sensor 49, a shift position sensor 51 for detecting the shift position of the main transmission portion 5c, an engine rotation sensor 52, a clutch pedal depression switch 53 for the main clutch 5a, and a vehicle speed sensor 54 are respectively connected.

  Further, on the output side of the traveling controller 46, a solenoid 56 for operating the shift control valve of the main transmission unit 5c, a solenoid 57 for operating the control valve for switching forward / reverse switching of the forward / reverse transmission unit 5b, a controller for a meter panel 58 are connected to each other.

  As shown in FIG. 8, on the input side of the work machine controller 61, a lever position sensor 62 for detecting the lever position of the work machine lifting lever 44, a handle angle sensor 63, a brake depression detection switch (left) 64, Two-wheel drive / four-wheel drive changeover switch 65, brake depression detection switch (right) 66, differential lock control on / off switch 67 for simultaneously turning on / off the front and rear wheel differential lock devices 37A, 37B, raising / lowering of the rotary tiller 12 and turning PTO A turning control on / off switch 68 for controlling on / off of the clutch is connected to each other.

  Further, on the output side of the work machine controller 61, a solenoid 69 for the work machine raising control valve, a solenoid 71 for the work machine lowering control valve, the flow control valve 18a in the brake valve 18 and the switching control valve 18b are operated. The solenoids 72s, 72l, 72r,..., A differential lock actuating control valve solenoid 73, a front wheel speed increasing control valve solenoid 74, and a front wheel constant speed control valve solenoid 76 are respectively connected.

In the control unit C of the tractor 1 configured as described above, various controls are executed as in the flowcharts showing the outline of the control program shown in FIGS.
When the power supply system of the tractor 1 is turned on, first, the detection values of various sensors and setting switches are read (step S1), then the shift control of the tractor 1 (step S2), and the front and rear wheel diff lock control (step S3). ), Turning control (step S4), PTO control (step S5), and the like are executed.

Details of the shift control (step S2) of the tractor 1 will be described.
The traveling transmission device 5e including the main transmission unit 5c and the sub transmission unit 5d is configured to be capable of multi-stage transmission from 1 to 8 stages. The transmission lever 15 switches the sub transmission unit 5c between high speed and low speed, When the shift up switch 47 or the shift down switch 48 provided in the grip is turned ON once, the speed is increased or decreased by one step.

  Further, when the shift up switch 47 and the shift down switch 48 are simultaneously turned on, the gear is shifted to a preset intermediate position, here, the fourth speed at any speed position from 1st to 8th. . In this way, it is possible to quickly move to the shift position intended by the operator while simplifying the configuration and simplifying the operation.

  Details of the differential lock control (step S3) will be described.

    In the differential lock control, as shown in FIG. 10, it is determined whether the differential lock control on / off switch 67 is on or off (step S11), and if there is an operation with the switch on, the lever position sensor 62 of the work implement elevating lever 44 continues. From the detected value, it is determined whether or not the work machine 12 is set to the raised position, that is, the non-work position when the switch 67 is turned on (step S12). When the switch 67 is turned on when the work machine 12 is in the raised position, the solenoid 73 of the differential lock actuation control valve is energized, and the differential lock cylinders 37a and 37b are actuated to differentially lock the front and rear wheels 2 and 3. The devices 37A and 37B are turned on (step 14), and then the operation thereof is turned on / off according to the turning on / off operation of the on / off switch 67.

  On the other hand, when the switch 67 is turned on when the work machine 12 is in the lowered position, it is assumed that the work machine 12 is in a working state and is loaded and cannot travel straight, and the work machine 12 is raised by the lever position sensor 62. That is, in a state where no load is applied, the solenoid 73 of the control valve for differential lock operation is energized, the differential lock devices 37A and 37B of the front and rear wheels 2 and 3 are turned off to facilitate turning, and the working machine 12 is raised. When the work machine 12 is lowered again, the differential lock device (37A, 37B) is turned on (step S13).

  In the controller 61, the steering wheel angle sensor 63 steers the front wheels 2 and 2 beyond a predetermined angle assuming a turning operation, the shift lever position sensor 49 assumes a position where the sub-shift stage is assumed to travel on the road, Here, when any one of the state where the “high” stage is detected and the state where the brake depression is detected by the brake depression detection switch 64 or 66 is detected, Even if 12 is lowered, the differential lock devices 37A and 37B are operated with priority.

  Thus, when the work implement is raised during turning in the field, the release operation of the diff lock devices 37A and 37B is facilitated to stabilize the straight traveling, and the steering wheel operation is facilitated and safety can be ensured when traveling on the road. Further, since the work machine 12 is lifted when traveling on the road, it is possible to prevent the diff lock devices 37A and 37B from being forgotten to be cut off, and the steering operability is not impaired.

  As another form of the differential lock control device, as a means for detecting the road running state, it may be a case where the detection speed of the vehicle speed sensor 54 exceeds a predetermined value. Further, when the depression of the clutch pedal is detected by the clutch pedal depression switch 53, the differential lock devices 37A and 37B may be turned off. Further, as a means for detecting the lift position of the work machine 12, it may be configured to detect by a lift arm angle sensor provided at the base of the lift arm 8.

  The differential lock control shown in FIG. 10 has a configuration in which both the front wheel 2 and the rear wheel 3 are differentially locked, and a configuration in which the differential lock devices 37A and 37B are turned on and off by a single switch 67. The switch 67 is turned on when it is easy to slip and it is desired to go straight, but if it is in the two-wheel drive state, a slip may occur on the side of the front wheel 2 and the field may be roughened. Therefore, it is necessary to immediately operate the 2WD 4WD switching clutch 5g of the 2WD 4WD changeover switch 65 to the 4WD side, and this operation may be troublesome.

Therefore, as shown in the flowchart of FIG. 11, when the differential lock on / off switch 67 is turned on, that is, when the front and rear wheels 2 and 3 are differentially locked, the two-wheel drive / four-wheel drive selector switch is in the two-wheel drive (2WD) state. It is now possible to automatically switch to 4WD (4WD) state even if 65 is switched. The 2WD state is when the 2WD 4WD switching clutch 5g is on the 2WD side.
When the diff lock on / off switch 67 is turned off (when the diff lock is released), control is performed to maintain the state as it is in the 4WD state, and to switch to the 4WD in the 2WD state. .
Thus, forgetting to cut when the diff lock devices 37A and 37B should be cut off is prevented, and the straight traveling performance and operability of the tractor are improved as compared with the prior art.

  Further, the rotation sensors 2S and 3S of the front and rear wheels 2 and 3 detect the rotation speeds of the front and rear wheels, respectively, and if there is any difference between the rotation speeds of the front and rear wheels, it is determined that the wheels are slipping automatically. A control mechanism is known in which a 4WD enters and automatically becomes a 2WD if there is no difference in the rotational speed of the front and rear wheels. If this control mechanism is called an automatic two-wheel drive / four-wheel drive selection mechanism, this automatic two-wheel drive / four-wheel drive selection mechanism can be used even when the diff lock on / off switch 67 is turned off, even when the tractor goes straight ahead. Operability and operability are improved.

  Further, the turning control described in step S4 of FIG. 9 is control performed when the turning control on / off switch 68 is turned on, and the steering angle of the front wheels 2 and 2 is turned by the detected value of the handle turning angle sensor 63. When it is detected that the vehicle is steered to the extent assumed to be an operation, the solenoid 69 of the control valve for raising the work implement is energized to raise the work implement 12 from the working position, and the solenoid 74 of the control valve for front wheel acceleration control. Is energized to drive the front wheel 2 at an increased speed, and the solenoids 72 of the flow rate control valve 18a and the switching control valve 18b of the brake valve 18 are energized to brake the rear wheel 3 inside the turn at a predetermined pressure. Is.

Next, the PTO control in step S5 in FIG. 9 will be described.
When a working machine such as the rotary working machine 12 is driven by power transmission from the PTO shaft 14, after the PTO on / off switch 45 is turned on, the engine rotation sensor 52, a foot pedal (accelerator pedal) or a throttle (not shown) The ratio between the current desired engine speed and the actual engine speed is calculated from the operating states of the throttle position sensor and the PTO rotation sensor that detect the position of the throttle valve that changes depending on the amount of lever operation. If the ratio is less than a certain ratio before and after connection, the PTO clutch 5i is worn or the work machine 12 may be in a heavy load state, so the PTO is turned off and the warning light blinks. . If the warning lamp continues to blink for a predetermined time, the controller 61 displays a warning and then the PTO clutch 5i is disengaged.

Further, the accumulated time (usage time) of the PTO connection is stored in the controller 61 separately from the hour meter of the tractor, and the energization time (cumulative use time) of the control valve for turning on and off the PTO clutch 5i is counted to engage the clutch. Displaying the time is desirable for protecting the PTO clutch 5i. This is because if the PTO clutch 5i is used for a long time, the disc may be worn, abnormal noise may be generated, and power transmission efficiency may be impaired.
By these controls, the work implement 12 can be operated without impairing the durability of the PTO clutch 5i.

Conventionally, the top link 10 of the tractor 1 has not been particularly configured to support this, and therefore it is inevitable that the top link 10 swings in the longitudinal direction of the vehicle body.
Therefore, as shown in the perspective views of FIGS. 12A and 12B, a holder 80 provided with a hook 80a for locking the intermediate portion of the top link 10 at the tip and a base portion of the holder 80 are notched in the notch of the hook bracket 81. The holder 80 is locked to the notch 81a of the bracket 81 with a spring 82 supported at one end by the bracket 81 and supported at the other end by the base of the holder 80. With the configuration, the holder 80 is fixed to the hook bracket 81 with a spring 82.

Since the hook bracket 81 is fixed to the upper surface of the case 43 a of the work machine elevating cylinder 43 with two M8 bolts, the top link 10 is securely held by the hook 80 a of the holder 80.
Thus, the top link 10 can be securely held by the hook bracket 81, the holder hook 80a, and the spring 82.

  The work vehicle of the present invention is highly likely to be used as an agricultural vehicle.

It is a side view of the tractor of an embodiment of the invention. FIG. 2 is a perspective view of the vicinity of a transmission lever of the tractor of FIG. The transmission block diagram of the tractor of FIG. The figure which shows the hydraulic circuit of the tractor of FIG. The figure which shows the hydraulic circuit of the tractor of FIG. The figure which shows the hydraulic circuit of the tractor of FIG. The block diagram which shows the connection state of the controller for working machines of the tractor of FIG. The block diagram which shows the connection state of the controller for driving | running | working of the tractor of FIG. The control flowchart of the whole tractor of FIG. The differential lock control flowchart at the time of raising / lowering the working machine of the tractor of FIG. The differential lock control flowchart of the 2WD and 4WD state of the tractor of FIG. The perspective view of the holding mechanism figure of the top link of the tractor of Drawing 1 (Drawing 12 (a) and Drawing 12 (b)).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tractor 2 Front wheel 2S Front wheel rotation sensor 3 Rear wheel 3S Rear wheel rotation sensor 4 Engine mounting frame 5a Main clutch 5b Forward / reverse transmission unit 5c Main transmission unit 5d Sub transmission unit 5e Traveling transmission device 5g 4WD switching device 5h Front wheel transmission shaft 5i PTO Clutch 5j PTO forward / reverse switching device 5k PTO transmission 6 Engine 7 Handle 8 Lift arm 9 Lower link 10 Upper link 11 Lift rod 12 Rotary work machine 13 Mission case 14 PTO shaft 15 Shift lever 16 Hydraulic pump 17 Ladies valve 18 Brake valve 18a Flow control valve 18b Switching control valve 19 Brake cylinders 21a, 21b Clutch control valve 22 Clutch cylinder 23 First shift control valve 24 First shift cylinder 26 Second shift control valve 27 Second shift cylinder 28 Sub shift control valve 29 Sub-transmission cylinder 31 2WD 4WD switching control valve 32 2WD 4WD switching cylinder 33 PTO speed change control valve 34 PTO speed change cylinder 36 Differential lock control valve 37A, 37B Differential lock device 37a, 37b Differential lock cylinder 38 External hydraulic pressure takeout device 39 Horizontal control Valve 41 Horizontal cylinder 42 Work implement elevating control valve 43 Elevating cylinder 43a Cylinder case 44 Work implement elevating lever 46 Travel controller 47 Shift up switch 48 Shift down switch 49 Shift lever position sensor 50F Front wheel differential device 50R Rear wheel differential device 51 Shift position Sensor 52 Engine rotation sensor 53 Clutch pedal pedal switch 54 Vehicle speed sensor 56, 57 Solenoid 58 Meter panel controller 61 Work machine controller 62 Lever position sensor 63 Sa 64 brake depression detection switch (left)
65 2WD 4WD selector switch 66 Brake depression detection switch (right)
67 Differential lock control on / off switch 68 Turning control on / off switch 69, 71, 72s, 72l, 72r, 73, 74, 76 Solenoid 80 Holder 81 Hook bracket 81a Notch 82 Spring C Controller

Claims (1)

The rotational power of the engine (6) is transmitted to the left and right front wheels (2) and the rear wheels (3) via a differential device (50F, 50R) equipped with a differential lock device (37A, 37B), and only the front wheel (2). Two-wheel drive / four-wheel drive switching device (5g) for switching between a two-wheel drive state in which the front and rear wheels (2, 3) are driven together, and a two-wheel drive / four-wheel drive switching actuator for switching the switching device (5g) In the work vehicle provided with (32),
A differential lock on / off switch (67) for turning on / off the differential lock device (37A, 37B);
Actuators (37a, 37b) for turning on / off the diff lock device (37A, 37B) by turning on / off the differential lock on / off switch (67);
If the two-wheel drive / four-wheel drive switching device (5g) is in the two-wheel drive state when the differential lock on / off switch (67) is turned on, it is switched to the four-wheel drive state, and when the differential lock on / off switch (67) is turned off, If the 4WD switching device (5g) is in the 4WD state, the 4WD state is changed to the 4WD state, and the 2WD 4WD switching device (5g) is not switched to the 2WD state until the 2WD state is reached. A work vehicle comprising the device (C).

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